Power transmission



June 18, 1940.

J. w. MARSH POWER mausmssxqn Filed la 15, 1937 6 Sheets-Sheet 1INVENTOR.

- ATTORNEY Jung 18, 1940. J, w. MARSH POWER TRANSMISSION Fila d lay 15,19s; 6 Sheets-Sheet 2 QW mu l :11 Q a N Nb Q Q QM I WM A V d I m IH Il{i r Wm QM 5. NM N mm V b 3 w i M A v y D B J NN m mw w o Jung 1-8, J.w. MARSH POWER TRANSMISSION 6 Sheets-Sheet 3 .Jdhn YA]. Marsh 0INVENTOR.

. g BY 8/ ATTORNEY 6 Sheets-Sheet 4 INVENTOR.

' ATTORNEY June 18,1940. .1. w. MARSH POWER TRANSMISSION Filed New 15,19s;

I .Jmhn WMarsh l @47 2M ma W m 2 2/ r E d T 6 VF k 4/ 0 z 7 w a 4 sSheets-Sheet 5' Patented June 18, 1940 PAT POWER TRANSMISSION John W.Marsh, Alexandria, Va., assignor to .Magee Marsh Corporation, acorporation of Delaware Application May 15, 1937, Serial No. 142,897

6 Claims.

This invention relates to certain improvements in power transmission andtorque transmitting devices and has for its object the provision of anovel mechanism comprising a combination of interrelated and cooperatingparts, whereby the power or torque from a single prime mover, or'aplurality of prime movers, is transmitted to a common driven shaft,selectively in either rotational direction, through a pair of clutchesor the like, and a plurality of speed ratios between the prime moversand the common driven shaft is obtained without the usual loss of torqueduring the transition periods as heretofore experienced with other speedchange mechanisms all accomplished with high efficiency.

Another object of the invention is'the production of a mechanism capableof providing two paths of power between a driving shaft, or a pluralityof driving shafts and a driven shaft, in combination with means forchanging speed ratios in either power path independently of the other.

A further object is to provide a power transmission and speed reducingmechanism, wherein the slow speed shafts, carrying the greater torque lare transverse to the high speed power input shaft or shafts, so thatthe'transition of power from shafts placed longitudinally of a vehicleto shafts placed transversely to said vehicle may be accomplished byrelatively'small high speed gearing as distinguished from relativelylarge low speed gearing.

A further object of the invention is to provide means for rotativelysynchronizing the speeds of shafts and gearing in a change speedmechanism, whereby a positive engagement of said gearing may beaccomplished without clashing or deleterious results.

' Another object of the invention is the provision of a mechanical geartransmission of the defined type wherein the gears are maintained attheir proper centers and alignment regardless of shaft distortions sothat the initial alignment and centers of the gears are maintained as inoriginal assembly and all members may be readily replaced with a minimumdisturbance of adjacent parts.

Another object'of the invention is to provide a transmission assemblyhaving multiple paths of power-flow through which the power may beselectively directed, with means in each power path for selectivelyvarying speed ratios, one independently of the other, and with furthermeans for operating said paths in either forward or reverse direction atany set speed.

Other objects of the invention will be apparent from the followingspecification when considered in connection with the accompanyingdrawings, to be hereinafter more specifically referred to.

Another object of this invention is a torque changing mechanism thatcomprises alternate paths of power, such as clutches, gearing, shafting,and the like, said alternate pathsof power being arranged so thatindependently of each other and selectively each alternate path whendisengaged can have its speed and torque changing characteristic fordelivery of the power from the input shaft to the output shaft varied atwill, and further, said alternate paths of power shall be provided withmeans that permit controllable overlap of the transmission of powerduring the period of transition wherein the power throughout is.transferred from one path to the other; i. e., so that, at the same timethat one alternate path passed from full engagement through partialengagement to complete disengagement,.the alternate path simultaneouslygoes from complete disengagement to partial engagement to fullengagement, and thereby securing continuity of torque delivery from theinput to the output shaft. Completion of each such transition results inone path completely engagedand the other path completely disengaged,suitable gripping mechanism being provided in each alternate path toaccomplish said engagement overlap and disengagement, so that highefliciency in a torque transmitting mechanism is achieved thereby.

Another object of the invention is the provision of a mechanical gearand shafting torque changing device, of the type defined, wherein theshafting in the operating condition is transmitting torsion only and isnot subjected to any bending or other forces resulting from the actionof the.

gearing and other power transmitting elements in the system when thegearing and other elements are transmitting power.

Another object of this invention is to provide a torque'changingmechanism including gripping members and means for selectively providingvariable speeds, all the operations of said transmission assembly beingactuated by fluid or gas under pressure arrangements selectively byremote control, thereby permitting complete power control of thenecessary actuating operations in such a single unit and further readilypermitting two or more units of that type to be selectively controlledfrom a single operating station.

One embodiment of the invention is illustrated in the accompanyingdrawings, in which:

Figure 1 isa side elevation of the gear assembly showing the relativeposition of the essential parts case, bearings, and other parts notessentially a part of this invention omitted.

Figure ,2 is a partial transverse sectional view of the mechanism online 2-2 of Figure 1, showing one "of the change speed transmissionshafts, the driven sh ft, and the common driving or main clutch sha tcarrying individual clutchesfor each change speed transmission shaft,bevel gears and reversing clutch all with their related gears andengaging clutches, the other change speed transmission shaft andconnecting gearing being omitdevice and clutch member ted for thepurpose of clearness in illustration.

Figure 3 is an enlarged detail sectional view illustrating the slidablyengaging clutch member and synchronizing mechanism carried by eachtransmission shaft between the change speed gears freely mounted on therespective shafts.

Figure 4 is an enlarged detail view on line 4-4 of Figure 3 showing theinternal mechanism of the clutch member and synchronizing device.

Figure 5 is an end view of the synchronizing as illustrated in Figures3, 4 and 6 and Figure 6 is a side view thereof.

Figure 7 is a fragmentary view of the synchronizer and clutch devicewith part of the shifting band removed showing in detail the slot andenlargement therein.

Figure 8 is a diagrammatic view of the mechanism set for forward motionin first and lowest speed ratio showing the path of power from thecommon clutch shaft to the final driven shaft.

Figure 9 is a similar view with the mechanism set for forward motion insecond speed ratio.

Figure 10 is also a diagrammatic view of the mechanism set for forwardmotion in third speed ratio and t Figure 11 illustrates the mechanismset for forward motion in fourth speed ratio, ,it to be understood thatwhile two final driven shafts are shown diagrammatically in eachfigure,'actually only one such driven shaft is used, the two shaftsshown being coincident in application as illustrated in Figure 1.

Figure 12 is a diagrammatic view of one means for operating the variousclutches.

Fig. 13 is a plan view of the slide valve 13 shown in Fig. 12; Fig. 14is a sectional view on the line |4-|4 of Fig. 13, and;

Fig. 15 is a sectional view on the line |5+J5 of Fig. 13.

Referring to the drawings in detail and particularly in Figures 1, 2 and8, the transmission comprises essentially a common main drive shaft I, achange speed or transmission shaft 2, a second change speed ortransmission shaft 3 and a common driven shaft 4.

These shafts 2 and 3 are referred to in some instances in the/ appendedclaims as "supplemental drive shafts.

Freely carried by the main drive shaft l, preferably at its intermediateportion, are a pair of bevel gears 5 and 6 and slidably keyed to thisshaft between said bevel gears is a clutch member 1 whereby thesegearsmay be selectively secured to said shaft for the purpose to behereinafter described.

Constantly in mesh with thebev el gears 5 and 6 are a pair of matingbevel gears 8 and 9 (Figures 8 to 11), which are the drivinggears'receiving their power from separate prime movers one arranged ateach end of the vehicle where is mounted. on a vehicle, it-to with theclutches removed and the supporting .be understood that in such casesthe main drive shaft change speed shafts 2 and 3 and the vehicle.

Where only one prime mover is employed of course only-one bevel gearsuch as 8 or 9 is used.

With this relation of the bevel gears 5 and 6 and 8 and 9 it will benoted that. said gears 5 and 6 will be .driven in opposite rotationaldirections andthe main drive shaft I can be rotated in either directionaccording to the engaged position of the clutch member 1.

Mounted on the opposite ends of the main drive shaft I are main clutchesI0 and II each clutch comprising generally an engaging part |2 secured'to said shaft and a cooperating clutch drum or the like l3 looselymounted on said shaft (Figure 2).. These clutch drums l3 are providedwith integral cylindrical extensions or sleeves I4 and I5 concentricallypositioned with respect to the shaft I and have secured thereto gears orthe like l6 and I respectively, said gears being of different diameters.be obtained from the shaft [according to the selective engagement of themain clutches I0 or II. These main clutches l0 and II are preferablyinterconnected so that gaged the other gaged. g

The change speed shafts 2 and 3 are preferably arranged parallel to. themain drive shaft and to each side and below said drive shaft, the shaft2 ,asillustrated, comprising the first and third speed shaft and shaft 3the second and fourth speed shaft this of course being a matter of geararrangement.

Secured to one end of change speed shaft 2 is a gear l8 in mesh withmain drive shaft clutch gear l6 and secured to one end of change speedshaft 3 is a similar gear l9 meshing with the other main drive shaftclutch gear IT. The gears 8 and I9 and I6 and I! are of the properdiamclutch is automatically disen-- eters to give the desired ratiosbetween these is a clutch member 24 whereby said pinions 20 and 2| maybe selectively engaged and locked to the shaft 2 according to the gearratio desired.

Similarly, the third and fourth change speed' shaft 3 is provided with aclutch member 25 slidably keyed thereto in position to engage theloosely mounted pinions 22 and 23 for selective speed change. Theseclutch members are of the same construction and design;' each includes asynchronizing device to be hereinafter described in detail.

The diagrammatic Figures 8 to 11 show two final driven shafts there isonly one driven shaft and this showing is merely. for the purpose ofillustration. The pinions 20 and 23, of the respective change speedshafts 2 and 3, are in mesh with a gear 26 secured to the final drivingshaft 4 and the pinions 2| and 22 of said shafts are in mesh with a'gear 21 also secured to the driven shaft 4.

whereby different speeds may.

4 but as hereinbefore stated as one clutch is enla the first and thirdReferring to Figure 2, all of the above mechanism is mounted in a caseor like housing 28 the ends of the lower or final driven shaft 4 beingprovided with antifrictional bearings 29 and the intermediate portionsof said shaft adjacent the pinions 26 and 21 being provided withantifrictional bearings 30 and 3| respectively, the extreme end portionsof the final driven shaft 4, extending outwardly from the case 28 beingprovided with the necessary driving connections such as cranks or thelike 3'.

As hereinbefore stated the cylindrical extensions Id and I5 of the mainclutch drums 13 have secured thereto gears 16 and H concentricallypositioned loosely on the opposite ends of the main drive shaft I andthis drive shaft is journalled in the upper portion of the case 28,antifrictional bearings 32 and 33 being interposed between therespective cylindrical extensions 14 and I5 of the main clutch drums l3and the case or housing. i

The bevel gears 5 and 8, also loosely mounted on the intermediateportion ofthe shaft 5, are provided with cylindrical extensions orsleeves 33 and 35 respectively and antifrictional bearings 36 and 31whereby said sleeves are freely mounted for rotation in the case orhousing 28 and concentrically positioned with respect to the main driveshaft 3, as clearly shown in Figure 2.

Located between the drive shaft 5 and the final driven shaft 4 are thechange speed shafts 2 and 3 but for the purpose of clearness inillustration, change speed shaft 2 and its pinions only is shown inFigure 2,'it to be understood that change speed shaft 3 would bedirectlybehind said shaft- 2. Gear i9 carried by change speed shaft 3, whichnormally would be in mesh with gear H has also been omitted.

Again referring to Figure 2, and the change speed shaft 2, that end ofsaid shaft having secured thereto the gear 18, is provided withantifrictional bearings 39 and the oppositeend of said shaft is,rotatably mounted concentrically within the hub of the pinion 2! uponantifrictional bearings 40. The pinion 2i is in turn antifrictionallymounted for rotation within the case 28 upon bearings ill. The otherpinion28,

- concentrically mounted for rotation about the shaft 2, isantifrictionally supported-in the case 28 by roller bearings or the like32. Both of these pinions 28 and 2| are supported independently of theshaft 2 within the case or housing 28 but are adapted to be selectivelylocked to said shaft by the sliding clutch member 24 as hereinbeforestated.

With the method and manner of antifrictionally mounting the variousshaft, gears and pinions within the case or housing 28, said gears andthe like will be unaffected by any warpage or distortion of the shaftsdue to external or intei nat strains, temperature changes or othercauses ungears 18 and I9 and under load are subject to der operativeconditions. Gear l8 being mounted on the splined end of shaft Zand gear69 similarly mounted on the splined end of shaft 3 said shafts are freeto warp or distort without affecting said torsional stress only. Alsothe mounting of shaft 4 will permit said shaft to expand relative to thecasing 28. It is also contemplated to divide the case 28 horizontallyalong the center line of shaft 4, whereby the lower section with shaft 5and associated parts may be removed independently of the othermechanisms within the case. It will be further noted that all the shaftsare readily removable and replaceable with a minimum disturbance ofassociated parts, particularly that the pinion 2i and the entiresynchronizing'and engaging clutch member 24 are readily removableandreplaceable through a cover plate 28'. In

addition, the frictional segments 5'! and 58 of the I synchronizingmechanism hereinafter described are removable from and replaceable onthe shell 33 with said shell and its associated mechanism in place. a I

With particular reference to Figure 3, the clutch member 24 is acombined clutch and synchronizlng' mechanism comprising a shell 63surrounding a splined engaging clutch portion 38 slidably mounted on' acorrespondingly splined section 84 of the shaft 2, and is adapted toselectively engage splines 38 and. 59 carried by the pinions 28 and 2|respectively.- This engaging portion M, is capable of longitudinalmotion with respect to the shell 43, but is resiliently restrained fromsuch longitudinal movement by a plurality of resiliently supported ballsmounted in the engaging clutch portion and cooperating annular grooves36, 31 and 38 formed in the internal periphery of the shell 53. Theshell 43 is also provided with a plurality of circumferentially spacedopenings or slots 39 (Figures 6 and '7 each having at its intermediateportion a semi-circular enlargement 50. Encircling the shell 33 is aclutch shifting ring or band 5| having a series of spaced holes or thelike 52 adapted to receive cooperating studs 53 projecting outwardlyfrom the engaging clutch portion 33, said studs passing through theslots 39 into said ring 5!, whereby upon a shifting of the ring iiithrough a shifting fork or the like (not shown) the splined engagingclutch portion 33 is moved longitudinally on the splined section 83 ofthe shaft 2 to engage either the first speed pinion 25 or the thirdspeed pinion 28 of said change speed shaft 2. Surrounding each stud 53is a roller 54, the'purpose of which will be hereinafter explained.

Secured to the pinions 2|! and 2i adjacent the ends of the shell 33 areannular friction members 55 and 56 respectively in positionto beselectively engaged by annular friction segments 51 and 58 secured tothe opposite ends of said shell 33. Al- I though this combined clutchand synchronizing device has been described with respect to changeclutch device, when the band or ring 5| is shifted longitudinally withrespect to shaft 2 in the direction of pinion 2!, this motion istransmitted through studs 53 to the splined engaging clutch portion 38,which owing to the engagement of the balls 85 with the groove 16, movesthe shell 33 until friction segments 58 engage the friction member'SGsecured to the pinion 2|. Since the pinion 2! is always in mesh with thegear 21 on the final driven shaft, said pinion will be rotated on itsshaft 2, as long as the complete transmission is in operation. As thefriction segments 58 engage the friction'member 56 the shell 43 will berotated until the rollers 54 on the studs 53 engage the enlargement 50in the slots 49. Further rotation of the shell 43 will be imparted tothe splined engaging'clutch portion 44 and to the shaft 2, gear I8,pinion I6 and clutch drum I3.

It will be apparent that any frictional torsional reactance betweensegments 58 and friction mem gitudinally in respect to the said clutchmechanism, will continue to urge frictional engagement between segments'58 and members 56 and not move-the splined clutch members 44longitudinally on the shaft 2. It will be further apparent that theforce tending to hold the rollers 54. in engagement with theenlargements 50 will be a function of the force required to accelerateor decelerate the shaft 2 and its related parts and that such force willcontinue to hold rollers 54 in engagement with enlargements 50 until therota tive speeds of pinion 2| and shaft 2 are equal, when the forceholding rollers 54 in engagement with said enlargements 50, will bereduced to an extent which will permit the longitudinal force applied toband 5| to move the splined clutch portion 44 longitudinally on theshaft 2 until the splines in the clutch portion 44 engage the splines 59on the internal periphery of the pinion 2|.

It will be evident, moreover, that the disengagement of rollers 54 fromthe enlargements 5|]- will give the splined clutch 44 a slight rotationrelative to the shell 43 and pinion 2|, thereby materially assisting inthe engagement of clutch splines with the splines 59. The longitudinalmovement of the splined clutch 44 relative to the shell 43 moves theballs 45 out of engagement with the groove 45 and at the completion ofthe travel of splined clutch 44 on shaft 2 engages balls 45 with thegroove 41, thereby centralizing shell 43 and maintaining disengagementbetween the friction segments 51 and 58 and friction members "55 and 56respectively.

The above described operation with respect to change speed shaft 2 andpinion 2| also applies to the clutching and declutching of change-speedshaft 2 and pinion 20 and to the gears and pinions on change speed shaft3.

With reference to the operation of the'transmission as a whole, when theprime mover. shafts .are turning in opposite directions, the motion ofboth will be transmitted to the bevel gears 5 and 6 by the bevel gears 8and 9 whereupon longitudinal movement of the clutch member I will secureeither bevel gear 5 or 5 to the main drive shaft I for forward orrearward motion of the vehicle as desired.

Thereafter either main clutch I or II can be engaged and disengaged atwill and the torque of the bevel gears and 5 as selected, can betransmitted to either main drive shaft gear l6 or II. Since gear 5meshes with the gear l8 on the change speed shaft 2 and gear I! mesheswith gear l9 on the change speed shaft 3, either change speed mechanismcan be engaged or disengaged at will from the bevel gear prime source orsources of power. With clutch l0 engaged and clutch disengaged, powerwill be transmitted through change speed shaft 2 to final driven shaft 4in first or .lowest speed ratio, as shown diagrammatically in Figure 8andpinions 22 and 23 in change speed shaft 3 will be idling, thereby'permitting synchronization through clutch member 25 and an engagement ofsaid shaft 3 with pinions 22. In this condition, as showndiagrammatically in Figure 9, the simultaneous disengagement of clutchl0 and engagement of clutch II will effect a change from first to secondspeed without loss of torque to the final driven shaft 4.

With reference to the clutches l0 and II, it is preferred that saidclutches be of a type provid-. ing a gradual and easy engagement anddisengagement to the extent of a slight slippage both upon engagementand disengagement, whereby an overlapping of engagement anddisengagement of the two clutches within allowable limits will bepermitted, tending towards a much smoother and efllcient operatingmechanism as a whole.

When the transmission is in second speed ratio, with clutch engaged anddriving through change speed shaft 3, pinions 20 and 2| on change speedshaft 2 are idling and by a movement of its synchronizing and engagingclutch member 24.

"the third speed gear 20 can be engaged to the change speed shaft 2, asillustrated diagrammatically in Figure 10. After this engagement, asimultaneous disengagement of clutch H and engagement of clutch-I0 willproduce a transition from second to third speed ratio without loss oftorque to the final driven shaft 4.

The change from third speed ratio to fourth speed ratio can besimilarlyaccomplished by disengaging pinion 22 and engaging gear 23 to changespeed shaft 3 as shown diagrammatically in Figure 11, after which clutchI0 is simultaneilpilsly disengaged with the engagement of clutch It isfurther noted that speed change ratios can be accomplished from high tolow ratios similarly to changing from low to high ratios without loss oftorque to the driven. shaft 4. The various clutch engagements requiredand the various gearing steps in the directions and speed ratiosprovided are summarized as follows:

Forward or reverse motion is accomplished by engaging clutch member 1,slidably mounted on drive shaft with either bevel gear 5 or 6.

First or lowest speed ratio-The following clutches are engaged: Mainclutch l0, clutch 24 to pinion 20. Power is transmitted through thefollowing gears and shafts: gears l6 and I8, shaft 2, gears 20 and 26,shaft 4.

Second speed ratio.The following clutches are engaged: Main clutchclutch 25 to pinion 23. Power is transmitted through the following gearsand shafts: gears l1 and I9, shaft 3, gears 23 and 26, shaft 4.

Third speed ratz'a-The following clutches are engaged: Main clutch I0,clutch 24 to pinion 2|. Power is transmitted through the following gearsand shafts: gears l6 and |8, shaft 2, gears 2| and 21, shaft 4. 1

Fourth or highest speed ratio-The following clutches are engaged: Mainclutch clutch 25 to pinion 22. Power is transmitted through thefollowing gears and shafts; gears fl and I9, shaft 3, gears '22 and 21,shaft 4.

' This shifting of the main clutches l0 and H and the supplementalclutches24 and 25, on the change speed shafts 2.and 3, is preferablyaccomplished by fluid pressure as diagrammatically illustrated in Figure12.

With particular reference to Figure 12 it will be noted that the mainclutches l0 and H- are provided with clutch operating shafts 65 and 65respectively. The outer ends of these shafts 65 and 65 are'formed aspistons, operating in cylinders 61 and 68, said pistons being urgedoutwardly by springs or the like 69 and respecdisengaged position.

Connected to the outer ends of these cylinders 61 and 08 are conduits IIand I2 running to a slide and a main clutch control valve I6, wherebyfluid under pressure may be admitted to the main clutch operatingcylinders BI and 56 through and under the control of the aforesaid slidevalve in the valve casing I3.

Still referring to Figure 12 it will be further noted that the clutches20 and 25 on the change speed shafts are also under the control of fluidpressure. The clutch 25 is provided with an operating lever 'IIconnected to a cross arm I8, the opposite ends of said arm beingprovided with pistons I9 and 80 operating in cylinders BI and 02respectively. The outer ends of these cylinders BI and 82 are incommunication with-conduits 83 and: 80 running to a control valvemechanism mounted in the valve casing I3 and opposing the action of thefluid pressure in the cylinders 8| I and 83 are expansion springs or thelike 85 and 86.

Likewise the clutch 24 is provided with an operating lever B'I connectedto a cross arm 88 carrying pistons 89 and 90, operating in cylinders 9iand 92 respectively, in communication with fluid pressure conduits 93and 95 running to the control valve mechanism in the valve casing I3said pistons 89 and 90 also being provided with expansion springs 95 and96 opposing the action of the fluid pressure.

The fluid pressure for these conduits 83, 84, 93 and 98 is suppliedthrough a main gear shift valve 9? by way of a conduit 98 incommunication with the control valve mechanism in the valve casing I3,the selective operation of the main clutches I and II and also thechange speed clutches 2d and 25 through theirproper fluid pressureconcluit, being controlled by the lever 99 operating any preferred typeof valve mechanisms within the casing I3. This particular form of. valvemechanism forms no part of the present invention .and it is thoughtunnecessary to illustrate the same in detail.

The main clutch control valve '18 and the main gear shaft valve 91 areeach connected to a common source of fluid pressure I00 and said valvesare provided with exhaust ports IM and I02 respectively whereby upon theclosing of communication between the main source of fluid pressure andthe fluid pressure conduits connected to the clutch operating fluidpressure oylinders, said conduits will exhaust back through the valvesI6 and 91 and the various clutches will be returned to their neutralpositions.

The structure of the slide valve by which I am enabled to properlyactuate the different clutches Is shown in detail in Figs. 13, 14 and15. In

these figures I have shown the valve body, indicated generally by thenumeral I3, having mounted thereon four plungers I03, I04, I and I06 andtransversely located plungers I01 and I08. Fluid under pressuredelivered to the valve body through the pipes 98, 14, I5 serves toactuate said plunger as hereafter described.

Slidably and rotatably mounted within th valve body is a member I09 towhich the gear shaft lever 99 is connected, the lever projecting througha cut-out I20 in the valve body, the cutout being so formed that thelever may be moved longitudinally and angularly as required. The slideI09 has a notch IIO on its lower surface shaped to accommodate theV-shaped upper ends of two of the plungers I03 to I06. In the positionshown in the drawings, fluid pressure a'dmitted through the pipe 90passes through pipes 94, 93 to the cylinders that actuate first andsecond gears, the ports III, H2, H3 and H4 providing connecting passagesto the pipes 04, 83, 93 and 84. In the positionshown in the drawings,pressure is being admitted through ports III, M2 to the respectivecylinders while ports I I 3, I14 are exhausting into the main exhaustpipe Isa.

The means for actuating the main clutch comprises the slide I09 havingon its squared portion H5 a ring H6 journalled in the portion III of thevalve body and provided with a pin extension H0. This pin engages a ballH9 in such manner that angular motion of the slide serves to transmitaxial motion to the plungers I01, I08 in a manner similarto that of aScotch yoke. With the shift lever 99 in central position as shown in thedrawings and with the main clutch valve IS in open position, pressure isadmitted through ports I08a, I0Ia. to the pipes I2, II and thus to themain clutches II, I0. When the shift lever is moved angularly to theleft, as viewed in Fig. 15, pressureis admitted through the port I010,to pipe II to actuate clutch I0 and to open when the control valvehandle is in central angu-' lar position. Such positive lap is necessarywhen the fluid medium is rapid in action, as for instance is compressedair, and when the characteristics of the clutches include relativelyslow engagement and rapid disengagement, to insure the engagement of oneclutch before the other disengages, it being the intent that one clutchshould pick up the load as the other relinquishes it. The exact amountof lap must be determined experimentally and will vary with the fluidmedium used, size and length of conduits, and clutch characteristics.Should the control valve handle be maintained in central angularposition, both clutches will be engaged and slipping. This procedure canbe used in starting a heavy load to distribute the wear between theclutches, but the normal operation will be to move the control handlefrom; extreme angular position to the other for which condition theamount of 'lap is determined.

From the preceding description, it will be apparent that angularmovement of the shift lever 99 controls the main clutch action whileaxial movement controls the gear shift clutches. The cut-out I20 in thevalve body is arranged to permit the engagement of either clutch whenfirst and second, second and third,-or third and fourth gears areengaged but toprevent the engagement of the wrong clutch duringtransition stages.

the other is disengaged and any desired overlap ping of engagement anddisengagement may be I obtained by the proper timing of the valvemechanisminthe valve casing 19 under the control of the [operating lever09. Furthermore, various gear shifting combinations are possible,through the devices just described for operating the clutches 24 and.25, dependent upon the construction and operation of the control valvein the valve casing 13.

For example, with the main clutch control valve 16 and main gear shiftvalve 91 open to exhaust the engine is started and warmed up. The valveoperating lever 99 is then moved to put change speed gear shiftingcylinders 92. and Bi, through conduits 94 and 83, in communication withconduit 98 to shift clutches l4 and 25 into first and second speedposition, upon the operation of valve 91 to the: position as shown. Asthe valve operating lever 99 is moved as above described, said movementalso establishes communication between conduit H of the clutch operatingcylinder 61 of main clutch in and the main clutch control valve 16, sothat as this valve is operated, following the operation of valve 91,driving connection will be established through shaft I gear I6 gear l8gear 2| and gear 21 on the driven shaft 4, as illustrated in Fig. '8,the

same being the first speed drive.

By a proper manipulation of the operating lever 99 and the main controlvalves 16 and 91, speed ratios from first to fourth speed may beobtained,

together with any desired overlapping of engagement and disengagement ofthe main clutches l0 and H, whereby various gear shifting operations canbe performed for changing speed ratios, and the main clutches can beengaged and disengaged without interruption to the flo'w of power orloss of torque from the driving element to the driven element.

The foregoing specification and accompanying drawings describe andillustrate one application of the basic principles of using a pluralityof power transmissions with speed changing mechanisms between a powerinput and a poweroutput mechanism, with means for transmitting powerthrough any of the transmissions or speed changing mechanisms.

It is of course to' be understood that theinvention is to be limited tothe detail construction and arrangement only so far as defined by thescope of the appended claims.

In the appended claims the'terms fdriving and driven clutch members ,are.used for convenience in designation. It should be understood, however,that a reversal of arrangement of the clutch parts is contemplated andthe claims should be so construed.

What I claim is:

1. In a transmission, the combination with an input main power drive anda driven member, of a series of supplemental power drives therebetween,a pair of main clutches for alternately connecting and disconnectingsaid main drive to any one of the supplemental drives, fluid pressuremeans for simultaneously operating'said main clutches, clutches forselective change speeds associated with said supplemental drives, fluidpressure means for operating said last mentioned clutches, andmechanical means for coordinating the respectivefluid pressure actuatingmeans.

2. In a transmission, the combination with an input main power drive anda driven member, of a series-of supplemental power d ives therebetween,a pair of main clutches for alternately connecting and disconnectingsaid main drive to anyone of the supplemental drives,-fluid pressuremeans for simultaneously operating said main clutches, clutches forselective change speeds associated with said supplemental drives, fluidpressure means for operating said change speed clutches and a commoncontrol means for all of said fluid pressure means.

3. In combination, a drive shaft having two power delivery points, twotransmission shafts, friction clutches for selectively connecting thetransmission shafts to the points of power delivery, fluid pressuremeans for simultaneously actuating said clutches to engage one to sub-'stantially the extent that the other is disengaged, change speed gearson said transmission shafts, with fluid pressure means for independentmanipulation of the gears of the separate transmissions, a driven shaftconnected to both said transmissions, and mechanical means forcoordinating the respective fluid-pressure-actuating means.

4. In a transmission, the combination of a drive shaft having aconnection to a prime mover, means for reversing the direction ofrotation of said shaft relative to the'rotation of the prime mover, twoclutches each having its driving member rigid with said shaft, twotransmission shafts each of which is permanently gear-connected to adriven member of said clutches, independently operable change-speedmechanisms applied to said transmission shafts, fluid pressure means forselectively actuating said clutches and said change speed mechanisms,and a common control means for all of said fluid pressure means.

5. In combination, a drive shaft, having a connection to a prime mover,means for reversing the direction of rotation of said shaft relative tothe rotation of the prime mover, two friction clutches, each having itsdriving member rigidly connected to said shaft, two transmission shaftshaving change-speed gears thereon, each of which shafts is permanentlygear-connected toa driven member of said friction. clutches,independently operable fluid pressure means for changing the ratio .ofthe gears of the respective transmission shafts, 'fluid pressure meansfor selectively actuating said friction clutches, and mechanical meansfor coordinating the respective fluid-pressure actuating means.

6. In combination,.a drive shaft having a connection to a prime mover,means for reversing the direction of rotation of said shaft relative tothe rotation of the prime mover, two friction clutches, each having itsdriving member rigidly connected to said shaft, two transmission shaftshaving change-speed gears thereon, each of which shafts is permanentlygear-connected to a driven member of said friction clutches,independently operable fluid pressure means for changing the ratio ofthe gears of the respective transmission shafts, and fluid pressuremeans for causing en-,

agement of one of said friction clutches and for causing disengagementof the other friction clutch. and common mechanical means for actuatingthe respective fiuid-pressure-actuating means.

JOHN W. MARSH.

